Ben Kersten celebrates winning the 1km time trial event in Melbourne on Thursday. The Australian won in 1:01.815. (AFP)

Melbourne: University student Caitlin McClatchey ended Libby Lenton’s dream of seven gold medals as Scotland celebrated their greatest Commonwealth Games swimming performance with two gold medals on Thursday.

Australia topped the medal tally at the end of Day I of the 18th Games with three of the 11 gold medals, just ahead of the proud Scots who restricted swimming’s world power to just one gold in the pool.

Australian euphoria from a well-received opening ceremony the night before had already been dampened by a drugs controversy before the Scots stole their thunder in the pool.

McClatchey surged home to upset Lenton in the women’s 200m freestyle final and less than an hour later, David Carry pulled off another stunner in a weakened men’s 400m freestyle to leave the Scots on top of the swimming medals table.

“It’s fantastic, I’m just so proud to be a Scot,” McClatchey said after the Scots doubled their entire gold medal haul from the pool at the 2002 Manchester Games.

Lenton had been on world record pace but faded as McClatchey mowed her down in a Games record of one minute 57.25 seconds.

“It’s impossible, so it’s a bit of pressure off,” Lenton said of her unlikely seven-gold target. Carry reeled in Welshman David Davies just before the final turn to win a weakened men’s 400m freestyle final in 3:48.17.

“It’s incredible... It’s the stuff dreams are made of,” said a jubilant Carry.

Canadian Andrew Hurd beat Davies for silver while Craig Stevens, the man who replaced an ailing Ian Thorpe, was fourth.

Australia won their only pool gold on day one when teenager Stephanie Rice upset favourite Brooke Hanson in the women’s 200m individual medley, Lara Carroll ensuring an Australian podium sweep.

New Zealander Moss Burmester’s teammates greeted his men’s 200m butterfly victory and Games record of 1:56.64 with a haka war dance.

South African then won the first leg of their swimming rivalry with the hosts when Roland Schoeman, Lyndon Ferns, Johannes Zandberg and Ryk Neethling claimed the men’s 4x100m freestyle.

Australian gained a measure of revenge over Scotland at the velodrome when Ben Kersten upset favourite Chris Hoy and England’s Jason Queally ? winners at the last two Olympics ? to win the blue riband 1-km time-trial.

“I never expected to win,” said Kersten, who rode despite a persistent back injury.

Olympic champion and world record holder Anna Meares earlier claimed Australia’s first gold medal of the Games when she won the women’s 500m time-trial in 34.326 seconds.

The Meares family had plenty to celebrate with sister Kerrie, the Manchester champion, securing bronze.

The English trio of Paul Manning, Rob Hayles and Steve Cummings prevented a clean sweep of Australian victories by completing a 1-2-3 in the 4000m individual pursuit.

A drug cloud hung over the hosts as Australian Sports Minister Rod Kemp confirmed that unidentified tablets had been found along with syringes and vials in rooms occupied by home weightlifters at the Australian Institute of Sport in Canberra.

The results of tests will likely be known on Friday.